1. Field of the Invention
The present invention relates to a microprocessor for verifying internal functions in an actual machine in accordance with a test program executed after a reset of the microprocessor, and to a processing method of the microprocessor.
2. Description of the Related Art
In a conventional microprocessor, a bootstrap is executed after the microprocessor is reset. This bootstrap is executed in a manner that a boot address previously prepared in each microprocessor is set in a program counter, and based on this boot address, the bootstrap program is loaded into the microprocessor from a memory such as, for example, a boot ROM. Therefore, the bootstrap program executed after the reset of the microprocessor depended on the boot address fixedly set for each microprocessor. Moreover, attributes of the memory accessed based on the boot address were also fixed.
According to a development evaluation of such a conventional microprocessor as described above, in some cases, although the bootstrap as described above is executed after the reset of the microprocessor, a normal operational state is not reached due to trouble generated in functions of the microprocessor. In such a case, the conventional microprocessor did not have a mechanism for setting another address in the program counter in place of the boot address after the reset, thus making it impossible to verify the functions of the microprocessor. Specifically, it was impossible to independently verify the various independent functions of the microprocessor by setting a test address to access a test program in the program counter in place of the boot address, the test program being prepared for the purpose of verifying the functions of the microprocessor in an actual machine after the reset thereof, and by accessing the test program to be executed based on the set test address.
As described above, the conventional microprocessor was unable to set an address other than the boot address in the program counter after the reset thereof, thus making it impossible to execute a program other than the bootstrap after the reset thereof. Therefore, if trouble was generated in the microprocessor, it was impossible to verify the functions of the microprocessor by executing the test program after the reset of the microprocessor.